July 13, 2000
01:00 AM (EDT)

News Release Number: STScI-2000-23

Hubble Watches Star Tear Apart its Neighborhood

July 13, 2000: The Hubble telescope has snapped a view of a stellar demolition zone in our Milky
Way Galaxy: a massive star, nearing the end of its life, tearing apart the shell
of surrounding material it blew off 250,000 years ago with its strong stellar
wind. The shell of material, dubbed the Crescent Nebula (NGC 6888), surrounds
the "hefty," aging star WR 136, an extremely rare and short-lived class of super-hot
star called a Wolf-Rayet. Hubble's multicolored picture reveals with unprecedented
clarity that the shell of matter is a network of filaments and dense knots, all
enshrouded in a thin "skin" of gas [seen in blue]. The whole structure looks like
oatmeal trapped inside a balloon. The skin is glowing because it is being blasted
by ultraviolet light from WR 136.

Q & A: Understanding the Discovery

1.
What do the images show?

Hubble's view [the multicolored picture taken by the Wide Field and Planetary Camera 2] covers a small region at the northeast tip of the nebula, roughly three light-years across. A picture taken by a ground-based telescope [lower right] shows almost the entire nebula. The whole structure is about 16 light-years wide and 25 light-years long. The bright dot near the center of NGC 6888 is WR 136. The white outline in the upper left-hand corner represents Hubble's view. The nebula resides in the constellation Cygnus, 4,700 light-years from Earth.

2.
How did the star, WR 136, produce the nebula?

WR 136 created this web of luminous material during the late stages of its life. As a bloated, red super-giant, WR 136 gently puffed away some of its bulk, which settled around it. When the star passed from a super-giant to a Wolf-Rayet, it developed a fierce stellar wind - a stream of charged particles released from its surface - and began expelling mass at a furious rate. The star began ejecting material at a speed of 3.8 million mph (6.1 million kilometers per hour), losing matter equal to that of our Sun's every 10,000 years. Then the stellar wind collided with the material around the star and swept it up into a thin shell. That shell broke apart into the network of bright clumps seen in the image. The present-day strong wind of the Wolf-Rayet star has only now caught up with the outer edge of the shell, and is stripping away matter as it flows past [the tongue-shaped material in the upper right of the Hubble image].